1. Field of the Invention
The invention relates to semiconductor devices, and more particularly, to radiation hardened drain source protected MNOS transistors.
2. Description of the Prior Art
Typical prior art drain source protected MNOS transistors included a layer of silicon oxide interposed between the semiconductor substrate and the silicon nitride layer. These devices also included a silicon nitride layer interposed between the conductive layer forming the gate terminal and the silicon oxide layer providing electrical insulation between these layers. When these prior art devices are subjected to relatively high radiation levels, electrical charges are believed to build up in the silicon oxide layer causing the electrical characteristics of the transistor to shift. This shift is relatively permanent, and could result in limiting the application of the prior art devices to situations in which these devices were subjected to relatively low radiation levels.